Page:Popular Science Monthly Volume 26.djvu/700

682 are putting themselves to sleep, and folding their filaments up against their petioles.

Early in the morning we start for our first night-station, the negro village of Laudat, seven miles from Roseau, in the mountains. We might go on horseback, but prefer a way that will give opportunity for close biological observations; so, having a negro to carry our baggage and botanical books, we start out, armed with umbrella, gun, and opera-glass, with which to scan inaccessible specimens in the tree-tops, on foot. As we pass through the cultivated lands, we admire the areca and cocoa palms, but are disappointed with the banana-trees, whose leaves have been torn to shreds by wind and rain, and find the bread trees at this season presenting but a sorry spectacle. The dark masses of the mango-trees make a better impression, and it is impossible to repress admiration of the calabash-trees (Crescentia cujete), with great pumpkin-fruits hanging from the tips of their slender limbs, and which are devoted to such varied uses: the fruit-pulp to be made into a vegetable viand; the pumpkin-shell into vessels and dishes of every sort; and the outer bark by the West Indian orchid-growers as the ground on which to cultivate their fancifully shaped floral treasures. As we examine the plants by the roadside, many of them stragglers from the sea-shore or from foreign parts, we are struck with the variety of the provisions by which they adapt themselves to resist the heat and aridity of the dry season. We have already mentioned the succulent stems and the condensed surface of the beach plants, and the leafless condition of the coral-tree (Erythrina), which other Leguminosæ also assume during the heats. These and other peculiarities for the same end are exhibited not in the same degree for all of the species, but with numerous individual variations according to the special circumstances of each particular plant, and in such a way as to demonstrate a capacity for individual adaptation. Here are, close together, two specimens of the Bryophyllum calycinum, one standing in the open sunlight, and the other under the shadow of an acacia-tree. The former plant has relatively small, thick leaves, the structure of which is seen under the microscope to be close and made up of palisade like cells; while the other one displays much thinner and more loosely built leaves, exposing many times as much surface to the light as its companion did. Another method of adaptation is shown in the posing of the surface of the leaves parallel to the sun's rays instead of perpendicularly to them. This position in profile sometimes occurs as a peculiarity of the species; is sometimes brought about by the version or folding of the leaf-blades; and is sometimes dependent upon periodical movements of the leaves, which seem to be provided with particular organs for the purpose, according to the intensity of the light. The profile position appears to be fixed in the shore-grapes, which we observed on the beach, in the sapoteas, and in some other species. The faculty of folding the leaves appears rather to be one of individual